0.7.2: il tasto del boost diventa Stop mentre e' in corso

In Home e in copertina: un tocco ferma il boost invece di farne ripartire un
altro (dalla copertina era il caso peggiore). Il conto alla rovescia ora prende
il posto del suggerimento nella stessa riga e con lo stesso carattere: prima,
essendo piu' alto, spingeva giu' i tasti delle azioni rapide.
Glifo di stop disegnato con scripts/make_glyphs.py. Catalogo 199 voci.

README.md

@@ -21,6 +21,9 @@ status, domestic hot water, and the house target temperature per zone.
   it ticking down from 30:00 to 00:00, and the cover page shows it in place of
   the hot water target. The seconds come from the plant's own boost end time, so
   the count is right even if the boost was started from somewhere else
+- **The boost button turns into *Stop*** while a boost is running, on the home
+  screen and on the cover: tapping it stops the boost instead of starting
+  another one
 - **Away mode with dates**: tapping *Away* opens a dialog where you pick the
   first and the last day (calendar, one tap each). The house is kept at 15 °C
   for that period and resumes its normal programme on the day you chose as the